This invention relates generally to turn signal cancellation mechanisms for automotive vehicles and specifically to a turn signal cancellation mechanism having an actuator and pawl therein.
In most automotive vehicles, it is common to have a turn signal cancellation mechanism which contains electrical switching components and functionally interfaces with a steering shaft assembly. Virtually all such mechanisms have a casing upon which a handle is pivotably mounted. This casing is usually disposed on the steering column such that various internal members can engage the steering shaft assembly. When a turn is to be made, the handle is pivoted in the direction of turning and is then engaged into a detented position where it remains latched until after the turn has been completed. After the turn has been completed, the switch is canceled and the handle is allowed to return to its original neutral position. Additionally, a variety of other electrical accessories, such as hazard lamp switches and windshield wiper switches, may be incorporated within the turn signal handle and casing.
There are many traditional constructions for these turn signal cancellation mechanisms and switches. One such device is configured from a pivoting handle and actuator which work in conjunction with a pawl and extension spring. The actuator has a pair of outwardly extending arms generally forming a semi-circle upon which the pawl is mounted to span therebetween. Furthermore, a spring loaded detent finger is affixed upon an end of each arm of the actuator for engagement with an adjacent one of a pair of detent formations formed within the outer casing. Moreover, the pawl has two enlarged half-moon-shaped wings projecting outwardly from a central cavity within which is a spring loaded plunger. Each wing is pivotably movable by engagement with an adjacent arm of the actuator. The extension spring engages the pawl central cavity proximate with the exposed portion of the plunger. Moreover, a cylindrical post projects from the central cavity of the pawl perpendicular to a plane defined by the wings and engages an adjacent portion of the casing. The post guides the linear movement of the pawl in relation to the casing. While this construction is an improvement in the art, it is large to package and requires a multitude of components, thus, necessitating extraneous assembly operations and additional cost.
Other conventional constructions are disclosed in the following U.S. Pat. No. 4,900,946 entitled "Multi-Function Switch for Automotive Vehicles," which issued to Williams et al. on Feb. 13, 1990; U.S. Pat. No. 4,840,078 entitled "Steering Device for Vehicles," which issued to Shitanoki on Jun. 20, 1989; U.S. Pat. No. 4,426,951 entitled "Turn Signal Cancellation Apparatus for Use with Steering Wheel and Shaft Assembly," which issued to Nishizima on Jan. 24, 1984; and, U.S. Pat. No. 3,914,566 entitled "Turn Signal and Hazard Warning Switch," which issued to Wendling on Oct. 21, 1975, all of which are incorporated by reference herewithin. In general, most traditional turn signal cancellation mechanisms are difficult to actuate while the vehicle is engaged in a gentle turn in a first direction when the vehicle operator desires to make a sharp turn in a second and opposite direction. These mechanisms will usually be prematurely canceled by the turned steering shaft assembly and prevent the desired pivoted and detented actuation of the device.
Accordingly, a turn signal cancellation mechanism is desired which is compactly packaged, contains fewer parts, can be cost effectively produced and assembled, and which can bypass the automatic cancellation feature.